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pythoncairopangopycairopangocairo

"stroke" required after "showing" Pango layout?

I have been chasing a problem between PyCairo and PangoCairo. The following code illustrates it:

import math
import cairo
import gi
gi.require_version('Pango', '1.0')
gi.require_version('PangoCairo', '1.0')
from gi.repository import Pango, PangoCairo

surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, 400, 400)
ctx = cairo.Context(surface)

# TOP LEFT CIRCLE
ctx.save()
ctx.arc(100.0, 100.0, 50, 0, 2 * math.pi)
ctx.set_source_rgba(0.0, 0.0, 1.0, 1.0)
ctx.set_line_width(2.0)
ctx.stroke()
ctx.restore()

# CENTER TEXT
ctx.save()
layout = PangoCairo.create_layout(ctx)
layout.set_font_description(Pango.font_description_from_string('Arial 10.0'))
layout.set_markup('<b>Foo Bar</b>', -1)
ctx.set_source_rgba(0.0, 1.0, 0.0, 1.0)
_, text_extents = layout.get_pixel_extents()
text_width, text_height = text_extents.width, text_extents.height
ctx.translate(200.0, 200.0)
ctx.translate(-text_width / 2, -text_height / 2)
ctx.move_to(0.0, 0.0)
PangoCairo.show_layout(ctx, layout)
# ctx.stroke() # WHY?
ctx.restore()

# BOTTOM RIGHT CIRCLE
ctx.save()
ctx.arc(300.0, 300.0, 50, 0, 2 * math.pi)
ctx.set_source_rgba(1.0, 0.0, 0.0, 1.0)
ctx.set_line_width(2.0)
ctx.stroke()
ctx.restore()

surface.write_to_png('test.png')

It results in the following picture:

two circles and text

My intention is to draw two circles and text. The line between the text and the bottom right circle is not intended to exist. I can make the line disappear by adding / uncommenting the ctx.stroke() call directly underneath PangoCairo.show_layout in the center text code block.

It works, but it does not feel right. The text does not require a line stroke. What is going wrong? Is the stroke actually required or have I made another mistake?

Solution

  • Try ctx.new_path() instead of ctx.stroke().

    Showing the layout seems to set the current point and thus the following line_to that arc does implicitly at its beginning actually shows a line.